When browsing a document hosted on an IP address, an attacker could insert certain characters to flip domain and path information in the address bar. This vulnerability affects Firefox < 77.

When performing add-on updates, certificate chains terminating in non-built-in-roots were rejected (even if they were legitimately added by an administrator.) This could have caused add-ons to become out-of-date silently without notification to the user. This vulnerability affects Firefox ESR < 68.10, Firefox < 78, and Thunderbird < 68.10.0.

When "%2F" was present in a manifest URL, Firefox's AppCache behavior may have become confused and allowed a manifest to be served from a subdirectory. This could cause the appcache to be used to service requests for the top level directory. This vulnerability affects Firefox < 78.

By navigating a tab using the history API, an attacker could cause the address bar to display the incorrect domain (with the https:// scheme, a blocked port number such as '1', and without a lock icon) while controlling the page contents. This vulnerability affects Firefox < 70.

By encoding Unicode whitespace characters within the From email header, an attacker can spoof the sender email address that Thunderbird displays. This vulnerability affects Thunderbird < 68.8.0.

When constructing a permission prompt for WebRTC, a URI was supplied from the content process. This URI was untrusted, and could have been the URI of an origin that was previously granted permission; bypassing the prompt. This vulnerability affects Firefox < 78.

The SELECT element implementation in Mozilla Firefox before 25.0, Firefox ESR 24.x before 24.1, Thunderbird before 24.1, and SeaMonkey before 2.22 does not properly restrict the nature or placement of HTML within a dropdown menu, which allows remote attackers to spoof the address bar or conduct clickjacking attacks via vectors that trigger navigation off of a page containing this element.

A possible vulnerability exists where type confusion can occur when manipulating JavaScript objects in object groups, allowing for the bypassing of security checks within these groups. *Note: this vulnerability has only been demonstrated with UnboxedObjects, which are disabled by default on all supported releases.*. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.

Mozilla before 1.7.6, and Firefox before 1.0.1, allows remote attackers to spoof arbitrary web sites by injecting content from one window into a target window whose name is known but resides in a different domain, as demonstrated using a pop-up window on a trusted web site, aka the "window injection" vulnerability.

The file-download implementation in Mozilla Firefox before 27.0 and SeaMonkey before 2.24 does not properly restrict the timing of button selections, which allows remote attackers to conduct clickjacking attacks, and trigger unintended launching of a downloaded file, via a crafted web site.

A missing delay in directory upload UI could have made it possible for an attacker to trick a user into granting permission via clickjacking. This vulnerability affects Firefox < 131, Firefox ESR < 128.3, Thunderbird < 128.3, and Thunderbird < 131.

If a custom mouse cursor is specified in CSS, under certain circumstances the cursor could have been drawn over the browser UI, resulting in potential user confusion or spoofing attacks. This vulnerability affects Firefox ESR < 102.5, Thunderbird < 102.5, and Firefox < 107.

Using the <code>S.browser_fallback_url parameter</code> parameter, an attacker could redirect a user to a URL and cause SameSite=Strict cookies to be sent.<br>*This issue only affects Firefox for Android. Other operating systems are not affected.*. This vulnerability affects Firefox < 107.

Mozilla Firefox before 26.0 and SeaMonkey before 2.23 do not properly consider the sandbox attribute of an IFRAME element during processing of a contained OBJECT element, which allows remote attackers to bypass intended sandbox restrictions via a crafted web site.

Mozilla Firefox before 25 allows modification of anonymous content of pluginProblem.xml binding

A bug in popup notifications' interaction with WebAuthn made it easier for an attacker to trick a user into granting permissions. This vulnerability affects Firefox < 126, Firefox ESR < 115.11, and Thunderbird < 115.11.

The timing of a button click causing a popup to disappear was approximately the same length as the anti-clickjacking delay on permission prompts. It was possible to use this fact to surprise users by luring them to click where the permission grant button would be about to appear. This vulnerability affects Firefox ESR < 115.6 and Firefox < 121.

When using the Performance API, an attacker was able to notice subtle differences between PerformanceEntries and thus learn whether the target URL had been subject to a redirect. This vulnerability affects Firefox < 103.

Mozilla Firefox 4.x through 11.0, Firefox ESR 10.x before 10.0.4, Thunderbird 5.0 through 11.0, Thunderbird ESR 10.x before 10.0.4, and SeaMonkey before 2.9 allow remote attackers to spoof the address bar via an https URL for invalid (1) RSS or (2) Atom XML content.

Even when an iframe was sandboxed with <code>allow-top-navigation-by-user-activation</code>, if it received a redirect header to an external protocol the browser would process the redirect and prompt the user as appropriate. This vulnerability affects Firefox < 102.

The Web Workers implementation in Mozilla Firefox before 23.0, Firefox ESR 17.x before 17.0.8, Thunderbird before 17.0.8, Thunderbird ESR 17.x before 17.0.8, and SeaMonkey before 2.20 does not properly restrict XMLHttpRequest calls, which allows remote attackers to bypass the Same Origin Policy and conduct cross-site scripting (XSS) attacks via unspecified vectors.

Requests initiated through reader mode did not properly omit cookies with a SameSite attribute. This vulnerability affects Thunderbird < 91.9, Firefox ESR < 91.9, and Firefox < 100.

The getUserMedia permission implementation in Mozilla Firefox before 22.0 references the URL of a top-level document instead of the URL of a specific page, which makes it easier for remote attackers to trick users into permitting camera or microphone access via a crafted web site that uses IFRAME elements.

Mozilla Firefox before 22.0, Firefox ESR 17.x before 17.0.7, Thunderbird before 17.0.7, and Thunderbird ESR 17.x before 17.0.7 do not prevent the inclusion of body data in an XMLHttpRequest HEAD request, which makes it easier for remote attackers to conduct cross-site request forgery (CSRF) attacks via a crafted web site.

Mozilla Firefox 3.5.1 and SeaMonkey 1.1.17, and Flock 2.5.1, allow context-dependent attackers to spoof the address bar, via window.open with a relative URI, to show an arbitrary file: URL after a victim has visited any file: URL, as demonstrated by a visit to a file: document written by the attacker.

The permission prompt input delay could expire while the window is not in focus. This makes it vulnerable to clickjacking by malicious websites. This vulnerability affects Firefox < 124, Firefox ESR < 115.10, and Thunderbird < 115.10.

Using a markup injection an attacker could have stolen nonce values. This could have been used to bypass strict content security policies. This vulnerability affects Firefox < 124, Firefox ESR < 115.9, and Thunderbird < 115.9.

When parsing internationalized domain names, high bits of the characters in the URLs were sometimes stripped, resulting in inconsistencies that could lead to user confusion or attacks such as phishing. This vulnerability affects Firefox < 94.

It was possible to recreate previous cursor spoofing attacks against users with a zoomed native cursor. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and Firefox < 95.

The 'Copy Image Link' context menu action would copy the final image URL after redirects. By embedding an image that triggered authentication flows - in conjunction with a Content Security Policy that stopped a redirection chain in the middle - the final image URL could be one that contained an authentication token used to takeover a user account. If a website tricked a user into copy and pasting the image link back to the page, the page would be able to steal the authentication tokens. This was fixed by making the action return the original URL, before any redirects. This vulnerability affects Firefox < 94.

WebExtensions with the correct permissions were able to create and install ServiceWorkers for third-party websites that would not have been uninstalled with the extension. This vulnerability affects Firefox < 95.

When invoking protocol handlers for external protocols, a supplied parameter URL containing spaces was not properly escaped. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and Firefox < 95.

By misusing a race in our notification code, an attacker could have forcefully hidden the notification for pages that had received full screen and pointer lock access, which could have been used for spoofing attacks. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and Firefox < 95.

Thunderbird unexpectedly enabled JavaScript in the composition area. The JavaScript execution context was limited to this area and did not receive chrome-level privileges, but could be used as a stepping stone to further an attack with other vulnerabilities. This vulnerability affects Thunderbird < 91.4.0.

Due to an unusual sequence of attacker-controlled events, a Javascript alert() dialog with arbitrary (although unstyled) contents could be displayed over top an uncontrolled webpage of the attacker's choosing. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

By displaying a form validity message in the correct location at the same time as a permission prompt (such as for geolocation), the validity message could have obscured the prompt, resulting in the user potentially being tricked into granting the permission. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

The Opportunistic Encryption feature of HTTP2 (RFC 8164) allows a connection to be transparently upgraded to TLS while retaining the visual properties of an HTTP connection, including being same-origin with unencrypted connections on port 80. However, if a second encrypted port on the same IP address (e.g. port 8443) did not opt-in to opportunistic encryption; a network attacker could forward a connection from the browser to port 443 to port 8443, causing the browser to treat the content of port 8443 as same-origin with HTTP. This was resolved by disabling the Opportunistic Encryption feature, which had low usage. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

Event handlers on "marquee" elements were executed despite a strict Content Security Policy (CSP) that disallowed inline JavaScript. This vulnerability affects Firefox < 50.1, Firefox ESR < 45.6, and Thunderbird < 45.6.

Through use of reportValidity() and window.open(), a plain-text validation message could have been overlaid on another origin, leading to possible user confusion and spoofing attacks. This vulnerability affects Firefox < 93, Thunderbird < 91.2, and Firefox ESR < 91.2.

Through a series of navigations, Firefox could have entered fullscreen mode without notification or warning to the user. This could lead to spoofing attacks on the browser UI including phishing. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

Mixed-content checks were unable to analyze opaque origins which led to some mixed content being loaded. This vulnerability affects Firefox < 92.

A malicious extension could have opened a popup window lacking an address bar. The title of the popup lacking an address bar should not be fully controllable, but in this situation was. This could have been used to spoof a website and attempt to trick the user into providing credentials. This vulnerability affects Firefox ESR < 78.9, Firefox < 87, and Thunderbird < 78.9.

An issue where a "<select>" dropdown menu can be used to cover location bar content, resulting in potential spoofing attacks. This attack requires e10s to be enabled in order to function. This vulnerability affects Firefox < 50.

Add-on updates failed to verify that the add-on ID inside the signed package matched the ID of the add-on being updated. An attacker who could perform a man-in-the-middle attack on the user's connection to the update server and defeat the certificate pinning protection could provide a malicious signed add-on instead of a valid update. This vulnerability affects Firefox ESR < 45.5 and Firefox < 50.

When choosing a site-isolated process for a document loaded from a data: URL that was the result of a redirect, Firefox would load that document in the same process as the site that issued the redirect. This bypassed the site-isolation protections against Spectre-like attacks on sites that host an "open redirect". Firefox no longer follows HTTP redirects to data: URLs. This vulnerability affects Firefox < 114.

A mechanism was discovered that removes some bounds checking for string, array, or typed array accesses if Spectre mitigations have been disabled. This vulnerability could allow an attacker to create an arbitrary value in compiled JavaScript, for which the range analysis will infer a fully controlled, incorrect range in circumstances where users have explicitly disabled Spectre mitigations. *Note: Spectre mitigations are currently enabled for all users by default settings.*. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

Application permissions give additional remote troubleshooting permission to the site input.mozilla.org, which has been retired and now redirects to another site. This additional permission is unnecessary and is a potential vector for malicious attacks. This vulnerability affects Firefox < 68.

When arbitrary text is sent over an FTP connection and a page reload is initiated, it is possible to create a modal alert message with this text as the content. This could potentially be used for social engineering attacks. This vulnerability affects Firefox < 66.

A mechanism where disruption of the loading of a new web page can cause the previous page's favicon and SSL indicator to not be reset when the new page is loaded. Note: this issue only affects Firefox for Android. Desktop Firefox is unaffected. This vulnerability affects Firefox < 50.

Mozilla Firefox before 48.0 does not properly set the LINKABLE and URI_SAFE_FOR_UNTRUSTED_CONTENT flags of about: URLs that are used for error pages, which makes it easier for remote attackers to conduct spoofing attacks via a crafted URL, as demonstrated by misleading text after an about:neterror?d= substring.